Why your balance gets worse after 40

The system in your body that helps you keep your balance goes downhill after age 40, a new study finds.

The study involved 105 people, ages 18 to 80, who underwent tests of their vestibular system, which is the system that helps people maintain balance and orient themselves. The system consists of several structures in the inner ear that monitor movements of the head, detect gravity and send signals to the brain.

In the tests, the participants sat in a chair on top of a platform that could generate small movements in different directions. They were asked to report when they perceived motion in a certain direction. The researchers measured the participants' "vestibular threshold," which is the smallest motion that the participants could perceive. Generally, the lower a person's vestibular threshold, the better their vestibular system is functioning.

The researchers found that the vestibular threshold in the people studied was increasingly higher after the age of 40. These thresholds increased up to 83 percent per decade after that age, the researchers said.

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The participants also took a balance test, in which they stood on memory foam for 30 seconds with their feet together and their eyes closed. It turned out that those with a higher vestibular threshold were also much more likely to fail the balance test — by needing to open their eyes or take a step to maintain balance — than those with lower thresholds.

Since failing the balance test is linked with an increased risk of falls , the findings suggest that a person's vestibular function substantially impacts his or her risk of falls, the researchers said.

Using data on the number of deaths caused by falls each year in the United States, the researchers estimated that, conservatively, problems with the vestibular system after age 40 contribute to more than 57,000 deaths each year.

"This [finding] is alarming," the researchers, from Massachusetts Eye and Ear hospital, wrote in their paper , which was published online Oct. 3 in the journal Frontiers in Neurology. "Given the rapid aging of the world’s population … the problem will rapidly grow much worse" unless existing efforts to improve diagnoses and treatment of vestibular problems, and prevention of falls, are accelerated, they said.